Codeforces 682A Alyona and Numbers (water problem, mathematics)

Test instructions: Given two numbers m,n, ask you to add up to 5 in multiples from 1 to N, and 1 to M, and ask how many you have.

Analysis: First calculate how many modulo 5 in M and N is from 0 to 4, and then, according to the permutation combination, the multiplication is less than equal to M and N and can be divisible by five number, and then add the rest.

The code is as follows:

#include <bits/stdc++.h>using namespace Std;typedef long long ll;const int aa = 1234567;const int bb = 123456;const int cc = 1234;int Main () {    int n, m;    while (CIN >> n >> m) {        int x = n/5, y = m/5;        int xx = n% 5, yy = m% 5;        ll ans = (ll) x * (LL) y * 5;        Ans + = xx * y + yy * x;        if (xx + yy >= 5)  ans + = (xx + yy)/5 + (xx + yy)% 5;        cout << ans << endl;    }    return 0;}

Codeforces 682A Alyona and Numbers (water problem, mathematics)